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  Hard-facing alloys having improved crack resistanceUSPTO Application #: 20070187369Title: Hard-facing alloys having improved crack resistance Abstract: Weld deposit compositions with improved crack resistance, improved wear resistance, and improved hardness are provided by controlling matrix grain size and balancing Titanium and/or Niobium with Carbon and/or Boron content. Additionally, the presence of coarse chromium carbides is drastically decreased to reduce the amount of check-cracking. Preferably, the weld deposit is produced from a flux-cored or metal-cored wire. The weld deposit characteristics include a matrix having a fine grain size, small evenly dispersed carbides within the matrix, and a small amount of Carbon in the matrix. (end of abstract) Agent: Harness, Dickey, & Pierce, P.l.c - St. Louis, MO, US Inventors: Ravi Menon, Jack Garry Wallin, Francis Louis LeClaire USPTO Applicaton #: 20070187369 - Class: 219076100 (USPTO) Related Patent Categories: Electric Heating, Metal Heating (e.g., Resistance Heating), For Deposition Welding (e.g., Coating Or Building Up) The Patent Description & Claims data below is from USPTO Patent Application 20070187369. Brief Patent Description - Full Patent Description - Patent Application Claims
FIELD [0001] The present disclosure relates to alloy compositions for arc welding and more particularly to weld deposit compositions suitable for hard surfacing that reduce cracking and increase wear resistance and hardness. BACKGROUND [0002] The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. [0003] Hard-facing relates generally to techniques or methods of applying a hard, wear resistant alloy to the surface of a substrate, such as a softer metal, to reduce wear caused by abrasion, erosion, corrosion, and heat, among other operational or environmental conditions. A variety of methods are available to apply the wear resistant alloy to the substrate, among which includes welding, where a welding wire is deposited over the substrate surface to produce a weld deposit that is highly wear resistant. The welding wire may include a solid wire, metal-cored wire or a flux-cored wire, wherein the metal-cored wire generally comprises a metal sheath filled with a powdered metal alloy and the flux-cored wire generally comprises a mixture of powdered metal and fluxing ingredients. Accordingly, flux-cored and metal-cored wires offer additional versatility due to the wide variety of alloys that can be included within the powdered metal core in addition to the alloy content provided by the sheath. [0004] One known welding wire material that is commonly used for hard-facing includes chromium carbides. While conventional chromium carbides provide good wear resistance, the weld deposits produced from chromium carbide welding wires can produce a cross-checking pattern in the hard weld deposit surface, which is undesirable due to an increased susceptibility to cracking from such patterns. Additionally, coarse chromium carbides contribute to check-cracking, which are cracks that develop perpendicular to a bead direction and accelerate abrasive wear. SUMMARY [0005] In general, weld deposits with improved crack resistance, improved wear resistance, and improved hardness are provided by using nucleation sites to control matrix grain size and by balancing Titanium and/or Niobium with Carbon and/or Boron content. Additionally, the presence of coarse chromium carbides is drastically decreased to reduce the amount of check-cracking. Preferably, the weld deposit is produced from a flux-cored/metal-cored wire, however, it should be understood that other types of welding consumables such as a solid wires or coated shielded metal arc electrodes may also be employed. The weld deposit characteristics include a matrix having a fine grain size, small evenly dispersed carbides within the matrix, and a small amount of Carbon in the matrix. Additional alloying elements are provided for desired properties of the weld deposit and are described in greater detail herein. [0006] In one form of the present disclosure, a weld deposit composition produced from a flux-cored or metal-cored welding wire is provided that comprises, by percent mass, between approximately 0.7% and approximately 2.0% Carbon, between approximately 0.2% and approximately 0.5% Manganese, between approximately 0.5% and approximately 1.1% Silicon, between approximately 2.0% and approximately 8.0% Chromium, between approximately 2.0% and approximately 6.0% Molybdenum, between approximately 2.0% and approximately 5.0% Tungsten, between approximately 2.0% and approximately 8.0% Niobium and Titanium, between approximately 1.0% and approximately 2.5% Vanadium, between approximately 0.2% and approximately 0.9% Boron, and a balance comprising Iron. In additional forms, the Carbon comprises approximately 1.1%, the Manganese comprises approximately 0.3%, the Silicon comprises approximately 0.8%, the Chromium comprises approximately 4.0%, the Molybdenum comprises approximately 4.0%, the Tungsten comprises approximately 3.5%, the Niobium and Titanium comprise approximately 3.2%, the Vanadium comprises approximately 1.8%, and the Boron comprises approximately 0.5%. [0007] In another form, a weld deposit composition produced from a flux-cored or metal-cored welding wire is provided that comprises, by percent mass, between approximately 0.7% and approximately 2.0% Carbon, between approximately 0.1% and approximately 0.5% Manganese, between approximately 0.7% and approximately 1.4% Silicon, between approximately 6.0% and approximately 11.0% Chromium, between approximately 0.5% and approximately 2.0% Molybdenum, between approximately 2.0% and approximately 8.0% Niobium and Titanium, between approximately 0.2% and approximately 1.0% Vanadium, between approximately 0.2% and approximately 0.9% Boron, between approximately 0.4% and approximately 0.8% Copper, and a balance comprising Iron. In additional forms, the Carbon comprises approximately 1.1%, the Manganese comprises approximately 0.3%, the Silicon comprises approximately 0.8%, the Chromium comprises approximately 9.0%, the Molybdenum comprises approximately 0.8%, the Niobium and Titanium comprise approximately 3.5%, the Vanadium comprises approximately 0.3%, the Boron comprises approximately 0.5%, and the Copper comprises approximately 0.6%. [0008] In yet other forms of the present disclosure, a flux-cored or metal-cored welding wire capable of producing a weld deposit having the above-mentioned elements and a welded structure having a weld deposit with the above elements is provided by the teachings of the present disclosure. [0009] Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. DRAWINGS [0010] The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. [0011] FIG. 1 is a cross-sectional view of a flux-cored or metal-cored welding wire constructed in accordance with the principles of the present disclosure; [0012] FIG. 2 is a perspective view of a welded structure having a hard-facing surface constructed in accordance with the principles of the present disclosure; [0013] FIG. 3 is a chart illustrating test results of compositions in accordance with the present disclosure compared with prior art compositions; [0014] FIG. 4 is a photomicrograph of a prior art chromium carbide weld deposit having a matrix with coarse chromium carbides; [0015] FIG. 5a is a photomicrograph of a weld deposit exhibiting a matrix having a fine grain size in accordance with the teachings of the present disclosure; and [0016] FIG. 5b is a photomicrograph of a second weld deposit exhibiting a matrix having a fine grain size in accordance with the teachings of the present disclosure. DETAILED DESCRIPTION [0017] The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. [0018] Weld deposits for use in hard-surfacing applications that produce improved crack resistance, improved wear resistance, and improved hardness are provided by controlling matrix grain size and balancing Titanium and/or Niobium with Carbon content according to the teachings of the present disclosure. Additionally, the presence of coarse chromium carbides is drastically reduced to reduce the amount of check-cracking. Preferably, the weld deposit is produced from a flux-cored wire, however, it should be understood that other types of welding consumables such as a solid wire or coated shielded metal arc electrodes may also be employed while remaining within the scope of the present disclosure. The weld deposit characteristics include a matrix having a fine grain size, small evenly dispersed carbides within the matrix, and a small amount of Carbon in the matrix. Additional alloying elements are provided for various properties of the weld deposit and are described in greater detail below. [0019] Referring to FIG. 1, a flux-cored or metal-cored welding wire capable of producing weld deposits according to the teachings of the present disclosure is illustrated and generally indicated by reference numeral 10. The flux-cored/metal-cored welding wire 10 includes a mild steel sheath 12 that is filled with a powdered metal alloy core 14. As shown in FIG. 2, the flux-cored/metal-cored welding wire 10 produces a hard-facing surface 20 when welded onto a substrate 22, to produce a welded structure 24 having improved crack resistance, wear resistance, and hardness. Continue reading... Full patent description for Hard-facing alloys having improved crack resistance Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Hard-facing alloys having improved crack resistance patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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